@depressedsoul- Shhhhh! But I like the way you are thinking. I suggest doing this on an old laptop that fits in your cooler bag and attaching a WiFi boosting antenna so that the signal will be strong within a 150 foot (50m) range and their chance of locating you will be greatly reduced.Very cheap to do and easy.
Edit: If money is not an issue then the suggestion from tim3I0rd is even better. Piratebox- or try this link
http://www.makeuseof.com/tag/build-wireless-dead-drop-file-sharing/